Limits on using Private DNS - Alibaba Cloud DNS - Alibaba Cloud Documentation Center

Limits on the built-in authoritative module

Item	Limit	Description
Maximum number of zones	500	Up to 500 zones can be added within each Alibaba Cloud account.
Maximum number of associated virtual private clouds (VPCs)	100	Up to 100 VPCs can be associated with a zone.
Maximum number of Alibaba Cloud accounts whose VPCs can be associated with a zone	200	VPCs of up to 200 Alibaba Cloud accounts can be associated with a zone.
Maximum number of Domain Name System (DNS) records	100,000 (regular zone)	By default, up to 100,000 DNS records can be added for a built-in authoritative acceleration zone or a built-in authoritative regular zone. If you want to add more DNS records, submit a ticket to increase the limit.
Maximum number of Domain Name System (DNS) records	100,000 (acceleration zone)
Weight setting	Not supported (regular zone)	If you configure multiple IP addresses for a hostname, after a DNS request for the hostname is sent, the IP addresses are returned based on weight settings to achieve load balancing.
Weight setting	Supported (acceleration zone)
Intranet DNS resolution based on custom lines	Not supported (regular zone)	You can configure custom IP addresses for the DNS requests that are sent from a specific internal CIDR block in the built-in authoritative DNS. For more information about the limits on custom lines, see the Limits section of the Line-based intelligent DNS resolution topic.
Intranet DNS resolution based on custom lines	Supported (acceleration zone)
Maximum number of DNS requests that an Elastic Compute Service (ECS) instance in a VPC can send per second	5,000	Up to 5,000 DNS requests can be sent by an ECS instance in a VPC per second. If the upper limit is exceeded, throttling may be triggered and service availability of 99.99% in the Service Level Agreement (SLA) may not be guaranteed.
Maximum number of DNS requests that all ECS instances in a VPC can send per second	Unlimited	The total number of DNS requests that all ECS instances in a VPC can send per second is not limited.
Maximum number of recursive DNS requests that an ECS instance in a VPC can send to the Internet per second	600	An ECS instance in a VPC can send up to 600 recursive DNS requests to the Internet per second. If the upper limit is exceeded, throttling may be triggered.
Maximum number of recursive DNS requests that all ECS instances in a VPC can send to the Internet per second	5,000	All ECS instances in a VPC can send up to 5,000 recursive DNS requests to the Internet per second. If the upper limit is exceeded, throttling may be triggered.
Batch operations	For more information, see the Limits section of the Perform batch operations topic.	Private DNS allows you to import multiple domain names, delete multiple domain names, import multiple DNS records, and suspend or enable multiple DNS records at a time.
Service address	For more information, see the Limits section of the Perform batch operations topic.	You can create an inbound endpoint to specify custom DNS server addresses of Private DNS. This prevents system-assigned DNS server addresses (100.100.2.136 and 100.100.2.138) from being identical to IP addresses in on-premises data centers when data centers access the DNS servers.
Wildcard intranet DNS resolution	-	Wildcard intranet DNS resolution is supported regardless of whether the recursive resolution proxy for subdomain names is enabled.

Limits on the format of a zone

A zone can be up to 200 characters in length and have at least one level set.
Note
The level sets are separated with periods (.). For example, a represents one level set, a.b represents two level sets, and a.b.c represents three level sets.
A zone can have up to 16 level sets.
A hostname can have up to 20 level sets.
Note
In conclusion, a fully qualified domain name (FQDN) can have up to 36 level sets.
The first-level set of a domain name, also known as the top-level domain name, can be 2 to 63 characters in length. The other domain names below the top-level domain name can be 1 to 63 characters in length.
Note
Take the domain name www.aliyun.com as an example. com can be 2 to 63 characters in length, aliyun can be 1 to 63 characters in length, and www can be 1 to 63 characters in length.
A reverse lookup zone ends with .in-addr.arpa

Limits on the forward module

Item	Limit	Description
Maximum number of endpoints within an Alibaba Cloud account	20	Up to 20 endpoints can be created within an Alibaba Cloud account.
Maximum number of forwarding rules within an Alibaba Cloud account	1000	Up to 1,000 forwarding rules can be created within an Alibaba Cloud account.
Number of IP addresses for an outbound endpoint	2 to 6	Two to six IP addresses can be configured for an outbound endpoint.
Maximum number of destination IP addresses that can be specified in a forwarding rule	6	Up to six destination IP addresses can be specified in a forwarding rule.
Maximum number of VPCs that can be specified in a forwarding rule	100	Up to 100 VPCs can be specified in a forwarding rule.
Maximum number of level sets for a forward zone	16	A forward zone can have up to 16 level sets. If you enter an invalid zone, an error message appears.